There is a conventional technique in which data communication devices are provided to an object, such as a locking mechanism in a house and to, for example, an arm of a user of the object, and data communication between the data communication devices is performed when the user touches a part (e.g., a door knob) of the locking mechanism and thereby a contact path passing through the user and the locking mechanism is formed. By using a so-called contact communication, it may be possible to achieve an improved security of the locking mechanism (for example, see Patent Documents 1, 2, 3).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-77735
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2001-223649
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2002-246987